1. Field of the Invention
The present invention relates to a banding packing machine and more particularly to a banding packing machine capable of transmitting, with high precision, an operation of a cam mechanism provided to carry out cutting, welding and the like for binding a band.
2. Description of the Related Art
In an automatic or semi-automatic banding packing machine, a band led from a band reel is wound upon an object to be packed and is then clamped, and subsequently, is returned to the band feeding side and is tightened. Thereafter, a bound portion is melted by a heater almost simultaneously with the cutting and is bonded by means of a press. The timing of these operations is usually made by means of a cam mechanism.
FIG. 11 shows the structure of a control portion for carrying out an operation such as clamp, welding, cutting and the like for a tip portion of a band based on the cam mechanism in a conventional banding packing machine.
In the control portion, a right presser member 5, a left presser member 6 and a middle presser member 7 are accommodated in a support block 52 in the vicinity of a face where an object to be packed is to be provided, and are supported on a pair of fixed plates 12 and 13 through a screw member 54 or the like.
The right presser member 5, the left presser member 6 and the middle presser member 7 have such a structure that rollers 14, 15 and 16 provided on lower ends thereof abut on separate cams fixed to one common cam shaft and a vertical movement is carried out in a predetermined timing according to the cams. The rollers 14, 15 and 16 are pulled toward the cam side with springs 17, 18 and 19 such that they are maintained in the abutment state on the cams.
The right presser member 5, the left presser member 6 and the middle presser member 7 according to the conventional art have been mainly formed cylindrically.
However, the cylindrical members are high workability and might be slightly rotated in the middle of the vertical movement. In this case, the clamping operation or the cutting operation of a cutter is not stabilized so that the operation and function of the presser member are adversely affected. In order to avoid such a situation, it is preferable that a detent mechanism for controlling a rotation should be provided separately. However, there is a problem in that the number of parts is increased or the mechanism is complicated.
Moreover, there have been known square-shaped members. In that case, four faces should be polished or corner portions should be perpendicular. Thus, the square shape needs more precise processings than the circular shape.
In consideration of the above-mentioned circumstances, it is an object of the present invention to provide a banding packing machine in which a right presser member, a left presser member and a middle presser member can be processed easily and the number of parts is decreased, and furthermore, they can be assembled readily with high precision and are not rotated during sliding.
In order to achieve the above-mentioned object, the present invention provides a banding packing machine in which a tip portion of a band is clamped, is returned from a band feeding side and is tightened and a band superposition portion is melted by a heater. The band feeding side is then cut and bonded in a process of causing a right presser member, a left presser member and a middle presser member arranged rectilinearly opposite to a slide table for freely appearing on a band traveling path constituted on a packing machine body to approach to or separate from each other through an operation of a cam mechanism, wherein a drum portion of at least the middle presser member provided in a central part in the right presser member, the left presser member and the middle presser member has a sectional shape of an almost track including a pair of circular arc portions opposed to each other and a pair of straight portions opposed to each other, and one of ends of each of drum portions in the right presser member and the left presser member which are opposed to the straight portions of the middle presser member is formed rectilinearly.
According to such a structure, it is sufficient that a processing of simply exposing a flat face from a circular shape is carried out. Therefore, the processing of obtaining precision can be performed comparatively easily and a rotation can be prevented without requiring a detent mechanism. Moreover, a distance between the right presser member and the left presser member can be reduced. Consequently, the size of a corresponding slide table can be reduced. Thus, the present invention can contribute to a reduction in the size of the structure.
In the banding packing machine according to the present invention, moreover, the drum portions of the right presser member, the left presser member and the middle presser member can also be accommodated in a support block having an integral structure in which three communicating or overlapping holes corresponding to their shapes are provided.
With such a structure, these three members are guided into the three communicating holes of the support block so that a vertical movement is carried out with a plane contact. Therefore, rotation of the three members is prevented in a reliable manner.
As described above, according to the banding packing machine of the present invention, the left presser member, the middle presser member and the right presser member are vertically moved while coming in contact with each other on a plane basis. Therefore, they are not rotated. Accordingly, it is possible to transmit, with high precision, the operation of the cam mechanism provided to carry out cutting, welding and the like for binding a band. Moreover, the portions of the presser members other than the planar portions are formed like a circular arc. Therefore, in the case in which the whole body is to be formed, it is sufficient that a circular shape is cut. Therefore, high workability can be obtained.
Furthermore, if these three members are accommodated in the support block, they are guided vertically while coming in contact with the planes with the outer peripheral side bound through the support block. Therefore, a possibility that the rotation might be carried out can be lessened still more.
According to the present invention, furthermore, the three members are caused to come in contact with each other on a plane basis. Therefore, it is possible to reduce the assembly width of the whole block including the right presser member, the left presser member and the middle presser member and to reduce a size, and furthermore, to decrease the width of the slide table to abut on the three members.
These objects as well as other objects, features and advantages of the present invention will become more apparent to those skilled in the art from the following description with reference to the accompanying drawings.